We tried to profuse the live monkey with microbeads conjugated with anti-endoglin antibody that is high specific for endothelial cell (EC) and to positively select the capillary EC from various organs. We have used two monkeys so far, and confirmed that the beads certainly bound to the endothelium in certain organs (kidney, spleen, and lung) at 30 min after the injection by immunostaining. However, the staining pattern was not specific for EC but also showed moderate staining in stromal cells. We succeeded to raise a flask of cells from kidney and spleen by 10 days culture in one experiment. Then, we analyzed the expression of EC-specific antigens (ICAM-2, CD31, VE-cadherin, angiotensin converting enzyme) on these cells, and found that cells originated from spleen or kidney contained about 20% and less than 1% of EC, respectively, from the expression of these EC-markers. We continued the culture of spleen-derived cells for additional 2 weeks, but found that the percentage of EC was markedly reduced to 2% after the 2 passages. In the next step, we are thinking to use another antibody and to use less perfusion time to decrease the percentage of cells contaminated in the initial cell population before